Radial piston pump

ABSTRACT

A ROTARY PISTON PUMP IS ADAPTED TO PUMP HYDRAULIC FLUID. A SHAFT, HAVING ECCENTRIC CAMS, IS ROTATED IN BEARINGS. THE CAMS ACT AGAINST PISTONS ACTING WITHIN CYLINDER BLOCKS. THE PISTONS MAY BE SPRING-LOADED. THE CYLINDER BLOCKS ARE ARRANGED IN ROWS FORMING AN ASTERISK (STAR) SHAPE ABOUT THE SHAFT. TWO ROWS SANDWICH A BASE PLATE HAVING AN OUTLET MANIFOLD. THE CASING MEMBERS ARE CLAMPED BY BOLTS AND THE CASING MEMBERS CLAMP THE ROWS OF CYLINDER BLOCKS AND BASE PLATE.

June 6, 1972 R. BRUNNER 3,667,868

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INVENTOR RUDOLF' BRUN'YER A ORA/E) United States Patent 3,667,868 RADIAL PISTON PUMP Rudolf Brunner, Baldham, Germany, assignor to Messrs. Heilmeier & Weinlein, Munich, Germany Filed Feb. 4, 1970, Ser. No. 8,681 Claims priority, application Germany, Feb. 11, 1969, P 19 06 773.3; Switzerland, Jan. 28, 1970, 1,202/70 Int. Cl. F04b 1/04, 23/06 US. Cl. 417-273 13 Claims ABSTRACT OF THE DISCLOSURE DISCLOSURE This invention relates to a radial piston pump, in particular for hydraulic systems.

In such radial piston pumps the cylinder blocks are arranged in asterisk shape around an eccentric shaft and the pistons disposed in the cylinders are actuated in the direction of their working stroke by cams positioned on the eccentric shaft while they are returned under the force of springs or by positive guidance. The expression asterisk shape is to include also the extreme case of radical arrangement of a single cylinder block at the eccentric shaft although, as a rule, three, five, or seven cylinder blocks will be distributed around the circumference of the eccentric shaft to form a star with the eccentric shaft having three, five, or as well. Such an astrisk arrangement constitutes a row of cylinder blocks distributed around the circumference of the eccentric shaft. A multiple-row radial piston pump, the only type with which the present invention is concerned, comprises a plurality of such stars or rows arranged successively on the eccentric shaft.

The cylinder blocks of such a radial piston pump are arranged within the pump casing in a bath of the hydraulic medium. The pump casing, accordingly, is provided with a suction opening for the hydraulic medium.

The invention relates to a radial piston pump of the type described above wherein a first row of cylinder blocks arranged in asterisk shape about a common eccentric shaft at one side of a base plate provided with an outlet manifold and a second row of cylinder blocks arranged in asterisk shape about the eccentric shaft at the other side of said base plate are disposed between two pump casing halves, in each of which the eccentric shaft is supported and which together form a pump casing enclosing also the base plate and being filled with a hydraulic medium, a high pressure pipe connected to the outlet manifold of the base plate passing through said pump casing to the outside.

In such a structure the base plate is made of steel or a similar high pressure resistant material, whereas the pump body or casing consists of a pressure casting or is made of another less pressure resistant material, including plastic material. One suction opening in one half of the pump casing is suflicient if the bath of the hydraulic medium communicates across the base plate through a corresponding passage or aperture in the base plate.

It is the object of the present invention to provide a radial piston pump as described above which is of compact structure and can be assembled easily and quickly, minimizing the expenditure for installation and material and, at the same time, affording the possibility of assembling a two-, four-, six-, eight-, or other multiple-row pump, as desired, from standard structural components.

For this purpose the invention provides that the two pump casing halves of the pump structure as described above are clamped against each other axially by means of clamping bolts and that the rows of cylinder blocks and the associated base plate are sandwiched on the clamping bolts and clamped together axially between the two halves of the pump casing.

Many variants are possible within the scope of the invention. For instance, multiple-row radial piston pumps may be constructed by arranging several two-row assemblies successively on the clamping bolts, each of the assemblies being composed of a first asterisk-shaped row of cylinder blocks, a base plate, and a second asteriskshaped row of cylinder blocks, all being clamped together by the two pump casing halves. The interior surface of the circumference of the pump casing formed by the two casing halves may even be spaced from the cylinder blocks and from each base plate. Finally, it is also possible for both pump casing halves to be clamped together without any positive centralizing means and by merely interposing a resilient seal.

Preferably the invention provides that with multiplerow radial piston pumps comprising several base plates, at either side of each of which there is arranged a row of cylinder blocks, all the outlet manifolds of the base plates are connected to a common main collecting pipe extending within the pump casing and leading to a common pump outlet. Although this pump outlet may be disposed at an end face of the pump, the more convenient location is at the pump circumference. However, it is likewise possible to connect different base plates to different pump outlets and thus provide the function of a plurality of pumps within one pump casing.

It is remarkable that the structure of the novel pump permits to fasten a connecting pipe of the high pressure outlets of different base plates at the base plates. This avoids the effect of a hydraulic force which would urge the two interconnected base plates apart if the connecting pipes were inserted loosely.

Moreover, the invention comprises different possibilities of a sealing engagement between the pump outlet and the circumference of the pump casing enclosing the bath of the hydraulic medium.

It should be noted that the invention is not limited to radial piston pumps comprising an even number of rows of cylinder blocks. It is possible, for instance, to connect additional rows of cylinder blocks through at least one adjacent row of cylinder blocks to a base plate by interconnecting the outletpipes of a plurality of cylinders in the axial direction of the pump.

The invention will be described further, by way of example, with reference to the accompanying drawings, III which:

FIG. 1 is an axial sectional elevation of a two-row radial piston pump embodying the invention;

FIG. 2 is a section of a transverse sectional elevation through the central plane of the base plate of the radial piston pump shown in FIG. 1, taken in the area where the pump outlet pipe is secured at the high pressure outlet of the base plate;

FIG. 3 is a side elevational view, partly in section, of a four-row radial piston pump embodying the invention;

FIG. 4 is a sectional view, partly in cross section through the central plane of a base plate and partly in cross section directly before one side surface of the base plate, showing the position where the pump outlet pipe is secured to the common high pressure outlet of the one base plate of the radial piston pump shown in FIG. 3;

FIG. 5 is an axial sectional elevation of a six-row radial piston pump embodying the invention;

FIG. 6 is a longitudinal sectional elevation similar to FIG. 1, showing a modified embodiment of a two-row radial piston pump embodying the invention;

FIG. 7 is a longitudinal sectional elevation of a fourrow radial piston pump constructed in accordance with the design principle of FIG. 1;

FIG. 8 is a longitudinal sectional elevation of a six-row radial piston pump constructed in accordance with the design principle of FIG. 1;

FIGS. 9 and 10 are fragmentary axial sectional views taken approximately on lines 99 and 10--10, respectively, of FIG. 11; and

FIG. 11 is a fragmentary transverse sectional view of a modification of the four-row radial piston pump shown in FIG. 7.

Even though the structural shape may vary slightly, the same reference numerals are used for corresponding structural elements throughout the various drawings of the two-, four-, and six-row radial piston pumps embodying the invention. Where differences are to be indicated between elements having similar functions, the respective reference numerals are followed by a small letter.

All six pump arrangements having different numbers of rows, as shown in FIGS. 1, 3, and 5 to 8, comprise an eccentric shaft 1 extending axially through the pump. The pump body or casing comprises two halves 3 and 5 made from aluminum pressure castings facing each other and with their edges abutting against each other. Each pump casing half 3 and 5 carries a main bearing 7 for the eccentric shaft 1. The latter projects only out of casing half 5, the projecting end constituting a drive stub shaft 9. A gasket 10 forms a seal between the eccentric shaft 1 and easing half 5.

Cylinder blocks 14 are provided which are arranged in asterisk shape and radially with respect to the eccentric shaft 1. As FIGS. 1 and 6 show, there are two such rows 12a and 12b of cylinder blocks; according to FIGS. 3 and 7 there are four rows 12a, 12b, 12c, and 12d; and according to FIGS. 5 and 8 there are six rows 12a, 12b, 12c, 12d, 12e, 12f. In each row there are, for instance, three, five, or seven cylinder blocks spaced evenly around the circumference of the eccentric shaft 1. For a detailed description of a suitable design of the cylinder blocks reference may be had to German Gebrauchsmuster (utility model) 6 600 315. Through inlet valves 16 disposed radially outwardly with respect to the eccentric shaft 1 the cylinder blocks suck in a hydraulic medium from a hydraulic bath surrounding the cylinder blocks within the pump casing and discharge the hydraulic medium under pressure through outlet valves 19 oriented parallel to the eccentric shaft 1. The piston stroke of each operating piston .18 arranged in the cylinder blocks 14 is prodced by earns 22 fixed on the eccentric shaft 1 and acting on the pistons 18 through ball bearings 24. The operating pistons 18 are returned by means of return springs 26 (FIGS. 1, 5, 7, and 8). As may be seen from the arrangement of corresponding cams 22 of successive rows of cylinder blocks, which cams are offset by relative to each other, the working cycle of the cylinder blocks of adjacent rows is likewise displaced by 180 so that at the instant demonstrated in FIG. 1 of the drawing the cylinder block 14 disposed in the plane of the drawing in row 12a comprises an operating piston which happens to be located at its lower or radially inner dead center, while the operating piston of the cylinder block 14 disposed in the plane of the drawing in the successive row 12b at that time is located at its upper or radially outer dead center. The same is true of the further rows of cylinder blocks of the pumps shown in FIGS. 3 and 7, respectively, and in FIGS. 5 and 8, respectively. Together with the uneven number of cylinder blocks provided per row this measure contributes to smooth running of the pump and uniform delivery.

The cylinder blocks 14 of the two rows 12a and 12b are arranged at either side of a steel base plate 30a formed with a system of bores 32 which serve as outlet manifold for the cylinder blocks of rows 12a and 12b adjacent the base plate 30a and which, therefore, are connected by portions 34 extending parallel to the eccentric shaft 1 to all the outlet valves of the cylinder blocks of these rows.

In a similar manner the four-row and six-row pumps shown in FIGS. 3 and 7, respectively, and 5 and 8, respectively, are provided between the cylinder block rows 12c and 12d with a second base plate 30b having an outlet manifold 32 for all the cylinder blocks 14 of rows 12c and 12d adjacent this base plate. In case of the sixrow pumps shown in FIGS. 5 and 8, finally, also the cylinder blocks 14 of the two rows 12:: and 12f are arranged at either side of a base plate 300 of similar structure as base plates 30a and 30b and provided with an outlet manifold 32 for the cylinder blocks of these rows.

With the exception of the embodiment shown in FIG. 6 all the base plates provided in the various types of pumps each carry a secondary bearing 36 for the eccentric shaft 1. However, in the two-row radial piston pump according to FIG. 1 this bearing 36 may be dispensed with and the eccentric shaft 1, then supported only by the two main bearings 7, may instead extend freely through a central aperture in the base plate 30a.

Narrow spacers 38 only are arranged in axial direction of the eccentric shaft 1 between the successive structural elements, namely between the half of the main bearing 7 fixed on the eccentric shaft and the cam 22 and the half of the ball bearing 24 fixed thereto pertaining to the first row 12a, the half of the secondary bearing 36 fixed on the eccentric shaft 1 and the cam and the half of the ball bearing fixed thereto pertaining to the next row 1212, etc. The axial length of all these members, the axial space requirement of all cylinder blocks and of the base plate(s) arranged between the same, as Well as the axial length of the two casing halves 3 and 5 are chosen such that the cylinder blocks of the various rows and the base plate(s) disposed between the cylinder blocks can be sandwiched and clamped by means of clamping studs 44 between annular end face portions 40 and 42 of the two pump casing halves 3 and 5. The clamping studs 44 extend parallel to the eccentric shaft 1 through the entire pump and at the same time serve to locate the cylinder blocks in radial direction and in circumferential direction. For this purpose the clamping sutds 44 engage in corresponding recesses in the cylinder blocks.

Upon clamping together of the pump casing halves 3 and -5 the peripheral portions 46 and 48 thereof surround not only the cylinder blocks 14 but also the base plate 30a or all base plates 30a, 30b, 304:, respectively. In the double-row radial piston pump according to FIG. 1 the free edges of the pump casing halves 3 and 5 meet in a butt joint at 50a. When in released condition, a sealing ring 52a inserted at the butt joint projects somewhat out of the flat abutment surface and is compressed under the compressive force as the pump casing halves are clamped together. If the drawing shows the sealing ring completely within the flat abutment surface, this is nothing but diagrammatic idealization. This arrangement does not provide for positive centralizing of the two pump casing halves with respect to each other since this is unnecessary in view of the fact that the overall arrangement results in selfcentralization.

Instead of the butt joint between the two pump casing halves a stepped arrangement may be provided, as shown at 50b in FIGS. 3 and to 8, without effecting positive centralizing of the two shell halves 3 and 5 relative to each other. With this arrangement the sealing ring 52!) inserted between the steps affords a certain degree of radial freedom. As will be understood from FIGS. 3 and 5, the relatively great axial length of portion 54 of casing half 5 extending over the outer periphery of the sealing ring 52b and some clearance 56 between said portion 54 and the axially adjacent portion of the stepped surface of easing half 3 warrant that also with this arrangement the cylinder blocks 14 and base plate(s) are properly clamped between the casing halves 3 and 5.

In case of the two-row radial piston pumps according to FIGS. 1 and 6 and of the four-row radial piston pump according to FIG. 7 the suction opening 60a, through which the hydraulic medium flows into the hydraulic bath enclosed by the pump casing 3, 5 is formed as an integral part of the pressure casting at the front end of easing half 3. The multi-row radial piston pumps according to FIGS. 3, 5, and 8 instead have the pump inlet 60b formed at the periphery of casing half 5. In a similar manner, the high pressure outlets of the radial piston pumps may be provided either at an end face of the pump or at the circumference thereof. The latter solution provides an especially compact structure of the pump and therefore has been chosen for all the embodiments represented in the present application.

Due to the fact that the output pressure of the pump is too high, the pump outlet cannot be formed integral with the pressure casting of the pump body, as is the case with the pump inlet. As none of the steel base plates in either embodiment forms part of the pump circumference, a separate high pressure pipe 70 constituting the pump outlet must be passed through the pump casing to the outside in sealing engagement with the pump casing.

There are various possibilities of connecting the base plate(s) to the high pressure pipe 70 which forms the pump outlet.

In case of the two-row radial piston pump shown in FIG. 1 and of the many-row radial piston pumps shown in FIGS. 7 and 8 the opening 72 provided in casing half 5, into which opening the high pressure pipe 70 forming the pump outlet is inserted in sealing engagement by means of sealing ring 74, is not disposed opposite the high pressure outlet 80a of the base plate 30a. Within the pump casing the pump outlet pipe 70 for this reason comprises a portion 82 bent at an angle and ending in an extension 84 or 184 to be fastened at the high pressure outlet 80a. An annular seal 86 is arranged between the extension 84 and the high pressure outlet 80a of the base plate 30a. Two fastening bolts 88 (FIG. 2), offset from the high pressure outlet 80a of the base plate in the circumferential direction thereof, serve for fastening the extension 84 to the base plate 30a. These fastening bolts 88 are easy to handle before casing half 3 is installed for, with this embodiment of the pump, the circumferential area 900 of casing half 5 does not overlie the high pressure outlet 80a of the base plate 30a or the fastening bolts 88.

FIGS. 7 and 8 show amplifications of the double-row structural design to constitute four-, six-, or corresponding multiple-row radial piston pumps. With these multiplerow pumps the extension piece 84 of the double-row arrangement according to FIG. 1 is replaced by a high pressure pipe extension 184 of the bent portion 82 reaching up to base plate 3% in FIG. 7 and to base plates 30b and 300 in FIG. 8, respectively. The individual high pressure outlets a of the various base plates, being sealed off by an annular seal 86 each, are connected to said pipe extension 184. Again it is essential that the pump casing halves 3 and 5 be arranged with radial clearance relative to the various base plates and rows of cylinder blocks and their high pressure connecting pipe 184.

FIGS. 3 and 5 show another arrangement of fourand six-row pumps to solve the problem of installation. On principle, this solution could also be applied to tworow radial piston pumps. A detailed description of this other installation arrangement will be given further below.

First, the combination of the various outlet manifolds 32 of the two or more base plates of multiple-row radial piston pumps according to FIGS. 3 and 5 will be described briefiy. As can be seen from these figures, a common high pressure outlet 90 for all the base plates is provided at base plate 80a. The high pressure outlets 80b of base plate 30b and of base plate 30c as well as of any further base plate are each connected to the common high pressure outlet 90 by a bridging high pressure pipe 92, being embodied by a single bridging high pressure pipe 92 where several base plates 30b and 300 are connected to the high pressure outlet 90 in a series arrangement as shown in FIG. 5. In any case the high pressure bridging pipe 92 is rigidly connected to the base plates, the high pressure outlet manifolds 32 of which it interconnects, as indicated by the brazing or welding lines 94 in the pipe sections forming the bridging pipe 92, see FIGS. 3 and 5. The tubular pipe sections of the bridging pipe 92 are connected in a manner not particularly specified in the present application by means of intermediary pieces 96b and 900 which are secured to the base plate 30b or 300, rsepectively, in a manner similar to that of extension 84 (FIG. 2).

At base plate 30a of the embodiment shown in FIG. 3 there is provided an extension 96a which corresponds to extension 84 of FIG. 2. Besides being connected to the high pressure outlet 80a of the base plate 30a and to the bridging pipe 92, this extension 96a is connected in radial direction in a straight line to the pump outlet pipe 70 with which it forms an integral structural unit. As may be gathered from FIG. 4, the extension 96a is mounted in the same manner as extension 84 according to FIG. 2. In this case, too, an annular seal 86 and two fastening bolts 88 offset in circumferential direction of the base plate 30a are provided. A portion bent at an angle of the pump outlet pipe 70, as shown in FIG. 1, is not needed with this arrangement since the high pressure outlet 80a of the base plate 30a is located, in radial direction of the eccentric shaft 1, directly opposite the aperture 102 in the circumferential portion 90b of casing half 5, which circumferential portion 90b in this case extends so far as to cover also base plate 30a.

Notwithstanding that extension of casing half 5, it is possible to insert a screwdriver or similar tool for manipulating the fastening bolts 88 through the circumferential portion 90b, because a relatively wide spacing is provided for this purpose between the pump outlet pipe 70 and the inner edge of the aperture 102 in casing half 5. With the high pressure pipe 70 installed in position this spacing all around approximately corresponds to half the width of the fastening bolt. The space is subsequently closed by an annular seal 164 which is overdimensioned in width and retained by a spring ring 106. During assembly the base plate 30a is rotated somewhat in circumferential direction with respect to casing half 5 so that the high pressure pipe 70 will abut at the one side against the edge of the aperture 102. Thereby the clearance opened at the opposite side is doubled and will correspond exactly to the dimension of the head of a fastening bolt 88, thus enabling a tool for handling the bolt to be inserted between the high pressure pipe 70 and the edge of the aperture 102. The other fastening bolt can be rendered accessible by relative rotation between the base plate 30a and easing half in the opposite sense.

The double-row radial piston pump according to FIG. 6 differs from all other radial piston pumps shown in that the high pressure pipe 170 leading out of the pump casing constitutes a rigid projection of the base plate 130a With this design the assembly is facilitated in that the base plate is formed as a particular ring member having a wide inner bore 172 which is dimensioned such that the base plate may be pushed over the adjacent ball bearing 24 so that, with casing half 5 removed, the rigid projection 170 may be pushed from inside into the aperture 72 in casing half 3.

FIGS. 9, and 11 illustrate a modification of the invention in which a four-row radial piston pump of the nature shown in FIG. 7 has different base plates 30a and 30b connected to different high pressure pump outlets, so that a unitary pump assembly will give the functions of two pumps.

A high pressure pump outlet 70 (FIG. 9) extends through and is sealed in an opening 72 in the peripheral part of casing half 5 and has a relatively long lateral extension 18411 which is connected near its end with the pressure manifold 32 of base plate 30b. A second high pressure pump outlet 71 (FIGS. 10 and v1) extends through and is sealed in a second opening 72a formed in the peripheral part of easing half 5 at a location spaced angularly away from the location of outlet 70. The second outlet 71 has a relatively short lateral extension 1 84b that is connected near its end with the pressure manifold 32 of base plate 30a.

Thus, according to the modification of the invention shown in FIGS. 9-11, the hydraulic fluid forced under high pressure from the two rows of cylinder blocks assembled on base plate 30a is pumped out through outlet 71, while the fluid forced from the two rows of cylinder blocks assembled on base plate 30b is pumped out separately through outlet 70.

What is claimed is:

1. A radial piston pump for hydraulic pressure systems, comprising mating hollow casing members which together form a pump casing adapted to hold a bath of hydraulic pressure fluid, a rotary shaft extending into said casing and supported rotatably therein by bearing means on opposite end portions of said casing members, at least one two-row assembly of radial piston pumps disposed about said shaft inside said casing, each said assembly including a base plate lying transverse to said shaft and provided with manifold for fluid under pressure and, at either side of said base plate, an asterisk-shaped row of cylinder blocks each of which contains a cylinder having a piston reciprocable radially therein and having a fluid outlet connected with said manifold, said shaft having eccentric means thereon for displacing the pistons in the cylinder blocks of each said row so as to pump fluid into the manifold of the related base plate, pipe means for fluid under high pressure connected with each said manifold and extending from it through said pump casing to the outside, and clamping bolts extending between opposite end wall portions of said casing members and clamping said casing members axially against each other, the two rows of cylinder blocks and the base plate between them of each said assembly lying entirely inside said casing within the space occupied by the fluid bath therein and being positioned in sandwiched relation on and clamped together axially along said clamping bolts between opposite inner end wall portions of said casing members.

2. A radial piston pump according to claim 1, a part of said pipe means being fastened to a peripheral portion of the base plate of each said assembly.

3. A radial piston pump according to claim 1, the largest diameter of the components of each said assembly being smaller than the inner diameter of the circumferential wall portions of said casing members.

4. A radial piston pump according to claim 1, said casing members having mating circumferential edge surfaces on respective circumferential wall portions thereof, said edge surfaces being clamped against each other in confronting relation With resilient sealing means disposed therebetween.

5. A radial piston pump according to claim 1, one of said casing members having an aperture extending through a circumferential wall portion thereof, the manifold of the base plate of each said assembly having an outlet located axially beyond the axial extent of said one cas ing member, said pipe means including a pump outlet fitted into said aperture in sealing engagement therewith, a pipe extending inside said casing at an angle from said pump outlet to said manifold outlet of at least one said assembly, and means fastening said pipe in sealed relation to said manifold outlet.

6. A radial piston pump according to claim 1, said eccentric means including an eccentric cam member on said shaft for each said row and an annular anti-friction hearing fitted upon each said cam member between the same and the radially inner ends of the pistons in the cylinder blocks of such row, the base plate of each said assembly having an annular anti-friction bearing fitted in a central bore thereof and fitting upon said shaft for additionally supporting said shaft.

7. A radial piston pump according to claim 6, the axial extent of each said eccentric cam member and said bearing fitted thereupon being smaller than the axial extent of the associated cylinder blocks, and annular spacers being fitted on said shaft between the successive cam members and bearings thereon.

8. A radial piston pump according to claim 1, one of said casing members having an aperture extending through a circumferential wall portion thereof, the base plate of one said assembly being disposed susbtantially in radial alignment with said aperture, said pipe means comprising a rigid tubular pump outlet projecting radially from said base plate through and sealed to the margin of said aperture.

9. A radial piston pump according to claim 1, said casing members being composed of a metal material or a plastic material that would not safely resist the output fluid pressure of the pump.

10. A radial piston pump according to claim 1, having a plurality of said two-row assemblies clamped one axially against another along said bolts inside said pump casing, with at least one said row of cylinder blocks of each said assembly bearing laterally against an adjacent said row of cylinder blocks of another said assembly.

11. A radial piston pump according to claim 10, said pipe means comprising a single pipe for fluid under pressure connected in common with the respective manifolds of the base plates of all said assemblies.

12. A radial piston pump according to claim 10, said pipe means comprising one pipe for fluid under pressure connected with the manifold of the base plate of at least one of said assemblies and a separate pipe for fluid under pressure connected with the manifold of the base plate of at least one other of said assemblies.

13. A radial piston pump according to claim 10, one of said casing members having an aperture extending through a circumferential wall portion thereof, the base plate of one of said assemblies being disposed substantially in radial alignment with said aperture, said pipe means comprising a pipe for fluid under pressure connected in common with the manifolds of the respective base plates of all said assemblies, a pump outlet disposed in said aperture, said pipe leading into said pump outlet, and means fastening said pump outlet to a peripheral portion of said one base plate, said aperture being sufficiently larger than said pump outlet in the circumferential direction of said casing that a clearance enabling manipulation of said fastening means from outside said one casing member may be provided between said pump outlet and the margin of said aperture, and resilient means fitted between said margin and said pump outlet for sealing the latter in said aperture.

References Cited UNITED STATES PATENTS 3,270,686 6/1966 Thompson 91--502 2,941,475 6/ 1960 Blair 417238 3,174,436 3/1965 Wanner 417273 10 FOREIGN PATENTS 934,560 10/ 1955 Germany 4v7533 1,058,195 3/1954 France 417-269 1,096,750 10/ 1956 Germany 417--273 WILLIAM L. FREEH, Primary Examiner U.S. Cl. X.R. 417-533 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,667,868 Dated June 6, 1972 Rudolf Brunner Assignor to Heilmeier and weinlein, a partnership of west Germany.

It is certified that error appears in the above identified patentand that said Letters Patent are hereby corrected as shown below:

Column 1, line 36, "radical" should read radial line 40, after "or insert seven arms, respectively. Of course, any other number is possible Column 3, line 72, "prodced" should read produced Column line 65, "sutds" should read studs Column 7, line 26, "VI" should read ll Signed and sealed this 29th day of August 1972.

(SEAL) Attost:

Em-IARD M.L*L.ITC%D3IX,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents 

